Forwarding tables for virtual networking devices

ABSTRACT

Systems, methods, and non-transitory computer-readable storage media for forwarding tables for virtual networking devices. The system first identifies local virtual machines hosted on a local host connected to the system, the system having virtual tunneling capabilities. The system then generates a forwarding table for the system. Next, the system populates the forwarding table with local entries including bindings for the local virtual machines hosted on the local host and adds a default route in the forwarding table pointing to a default forwarder function, wherein the default route is configured to handle all non-local traffic relative to the system and the local host.

TECHNICAL FIELD

The present technology pertains to forwarding tables, and morespecifically pertains to forwarding tables for distributed virtualnetworking devices.

BACKGROUND

The soaring demand for network data throughout the globe has steadilyfueled the evolution of networking technologies, as engineers andmanufacturers rush to keep pace with the changing data consumptionlandscape and increasing network scalability requirements. Variousnetwork technologies have been developed precisely to meet this soaringdemand for network data. For example, overlay network solutions, such asvirtual extensible local area networks (VXLANs), as well asvirtualization and cloud computing technologies, have been widelyimplemented in networks with increasing success as popular solutions tosuch growing demands for network data.

However, while this advancement in network technologies has allowednetworks to support such increased demand for network data, it has alsoresulted in larger and more complex networks, involving massive amountsof traffic data constantly being routed through the network. And as theamount of traffic handled by the network grows, it becomes increasinglyimportant to ensure efficient and error-free routing strategies.Precisely, poor routing strategies can create an enormous burden on thenetwork, which only worsens as the amount of traffic grows, and canresult in inefficient and costly traffic routing, as well as routingerrors, such as route flaps and network loops. To this end, forwardingtables are typically implemented in networks to ensure that networkingdevices, such as routers and switches, can properly route trafficthrough the network. Unfortunately, as the complexity of the networkgrows, it becomes increasingly difficult to manage and maintain accurateand effective forwarding tables, particularly as virtual networks anddevices are integrated into the network.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which the above-recited and otheradvantages and features of the disclosure can be obtained, a moreparticular description of the principles briefly described above will berendered by reference to specific embodiments thereof which areillustrated in the appended drawings. Understanding that these drawingsdepict only exemplary embodiments of the disclosure and are nottherefore to be considered to be limiting of its scope, the principlesherein are described and explained with additional specificity anddetail through the use of the accompanying drawings in which:

FIG. 1 illustrates an example network device according to some aspectsof the subject technology;

FIGS. 2A and 2B illustrate example system embodiments according to someaspects of the subject technology;

FIG. 3 illustrates a schematic block diagram of an example architecturefor a network fabric;

FIG. 4 illustrates an example overlay network;

FIG. 5 illustrates a schematic block diagram of an exampleimplementation of a forwarding policy according to one embodiment;

FIG. 6 illustrates an example forwarding table implementing a defaultforwarding function scheme; and

FIG. 7 illustrates an example method embodiment.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Various embodiments of the disclosure are discussed in detail below.While specific implementations are discussed, it should be understoodthat this is done for illustration purposes only. A person skilled inthe relevant art will recognize that other components and configurationsmay be used without parting from the spirit and scope of the disclosure.

Overview

Data centers and networks are increasingly being built using virtualmachines (VMs), virtual switches and routers, and physical networkingdevices with virtualization capabilities, such as virtual tunnelendpoints, in order to increase the size and capabilities of thenetwork(s) by adding devices and virtual workloads using virtualization(e.g., overlay networks). Such virtualization devices often stack insidea hypervisor to forward packets inside of the host machine, or acrosshost machines by leveraging an overlay network technology, such asvirtual extensible LAN (VXLAN) technology. However, the forwardingtables on these devices are increasingly becoming larger and morecomplicated over time. For example, these devices typically maintain aforwarding table which includes reachability information, such astenant, VM network, or VM, for all of the VMs in the network, includingVMs across multiple hosts in an overlay network. This bindinginformation is sometimes referred to as a directory.

Such directory, however, can become extremely large and complicated, andthe sharing of information for populating the various directories oftensaturates the network(s). One of the reasons a complete directory ismaintained across devices is to prevent flooding of unknown trafficinside the data center. However, pushing this directory information, aspreviously suggested, can be an expensive operation in the control planeand may limit the size of the network.

The approaches set forth herein, on the other hand, can provide aforwarding scheme which eliminates many of these disadvantages ofconventional schemes. In particular, the forwarding scheme allowsforwarding tables on devices to be limited in size and complexity,without requiring extensive amounts of information to be pushed throughthe network or limiting the size of the network. In addition, theforwarding scheme can be implemented in a simplified and effectivemanner, while retaining the benefits of no flooding, and all otherbenefits of maintaining a complete forwarding table as is done inconventional schemes.

Disclosed are systems, methods, and computer-readable storage media forforwarding tables for virtual networking devices. Here, a networkingdevice first identifies virtual machines hosted on a local hostconnected to the networking device, where the networking device is avirtual tunnel endpoint associated with an overlay network. In somecases, the networking device is a virtual switch or virtual router. Inother cases, the networking device is a physical switch with virtualtunnel endpoint functionalities.

The virtual machines can reside on one or more segments of the overlaynetwork, such as VNIDs or VLANs. In some cases, the overlay network canbe a VXLAN network. However, in other cases, the overlay network can bebased on any other overlay protocol, such as NVGRE or STT, for example.The local host can be a server connected to the networking device andrunning the virtual machines. For example, the local host can be aserver running a hypervisor with one or more virtual machines. Here, thevirtual machines can reside on the overlay network.

In identifying the virtual machines, the networking device can obtainany of the routing information of the virtual machines, which caninclude, for example, the IP address of the virtual machines, the IPaddress of the local host, the MAC address of the local host, thenetwork and/or network segment identifier (ID), a routing domain ID,etc. In some cases, the networking device can also compare routinginformation collected with its own configured networking information,such as subnet, IP address, network segment, routing domain, etc., todetermine if the routing information should be treated as local forpurposes of the forwarding policy, as described below.

Next, the networking device generates a forwarding table (702). Theforwarding table can be a lookup table used by the networking device toroute or forward packets it receives. To this end, the networking devicecan use the forwarding table to determine where to send an incomingpacket it receives. In other words, the forwarding table can help thesystem 110 identify the next hop for the packet. Accordingly, theforwarding table can have hop information and mappings or bindings.

The networking device then populates the forwarding table with localentries including bindings for the virtual machines hosted on the localhost and adds a default route in the forwarding table pointing to adefault forwarder function configured to handle all non-local trafficrelative to the networking device and the local host. The defaultforwarder function can be implemented on any network, including anetwork separate from the overlay network, such as the overlay-awarenetwork fabric. Thus, the networking device can include all of the localentries in the forwarding table and a default route for all othertraffic. This way the networking device can maintain a smaller and lesscomplex forwarding table, by limiting the table to local entries and a“catch all” or default route for all other addresses and devices.

DESCRIPTION

A computer network is a geographically distributed collection of nodesinterconnected by communication links and segments for transporting databetween endpoints, such as personal computers and workstations. Manytypes of networks are available, with the types ranging from local areanetworks (LANs) and wide area networks (WANs) to overlay andsoftware-defined networks, such as virtual extensible local areanetworks (VXLANs).

LANs typically connect nodes over dedicated private communications linkslocated in the same general physical location, such as a building orcampus. WANs, on the other hand, typically connect geographicallydispersed nodes over long-distance communications links, such as commoncarrier telephone lines, optical lightpaths, synchronous opticalnetworks (SONET), or synchronous digital hierarchy (SDH) links. LANs andWANs can include layer 2 (L2) and/or layer 3 (L3) networks and devices.

The Internet is an example of a WAN that connects disparate networksthroughout the world, providing global communication between nodes onvarious networks. The nodes typically communicate over the network byexchanging discrete frames or packets of data according to predefinedprotocols, such as the Transmission Control Protocol/Internet Protocol(TCP/IP). In this context, a protocol can refer to a set of rulesdefining how the nodes interact with each other. Computer networks maybe further interconnected by an intermediate network node, such as arouter, to extend the effective “size” of each network.

Overlay networks generally allow virtual networks to be created andlayered over a physical network infrastructure. Overlay networkprotocols, such as Virtual Extensible LAN (VXLAN), NetworkVirtualization using Generic Routing Encapsulation (NVGRE), NetworkVirtualization Overlays (NVO3), and Stateless Transport Tunneling (STT),provide a traffic encapsulation scheme which allows network traffic tobe carried across L2 and L3 networks over a logical tunnel. Such logicaltunnels can be originated and terminated through virtual tunnel endpoints (VTEPs).

Moreover, overlay networks can include virtual segments, such as VXLANsegments in a VXLAN overlay network, which can include virtual L2 and/orL3 overlay networks over which VMs communicate. The virtual segments canbe identified through a virtual network identifier (VNI), such as aVXLAN network identifier, which can specifically identify an associatedvirtual segment or domain.

Network virtualization allows hardware and software resources to becombined in a virtual network. For example, network virtualization canallow multiple numbers of VMs to be attached to the physical network viarespective virtual LANs (VLANs). The VMs can be grouped according totheir respective VLAN, and can communicate with other VMs as well asother devices on the internal or external network.

Network segments, such as physical or virtual segments; networks;devices; ports; physical or logical links; and/or traffic in general canbe grouped into a bridge or flood domain. A bridge domain or flooddomain can represent a broadcast domain, such as an L2 broadcast domain.A bridge domain or flood domain can include a single subnet, but canalso include multiple subnets. Moreover, a bridge domain can beassociated with a bridge domain interface on a network device, such as aswitch. A bridge domain interface can be a logical interface whichsupports traffic between an L2 bridged network and an L3 routed network.In addition, a bridge domain interface can support internet protocol(IP) termination, VPN termination, address resolution handling, MACaddressing, etc. Both bridge domains and bridge domain interfaces can beidentified by a same index or identifier.

Furthermore, endpoint groups (EPGs) can be used in a network for mappingapplications to the network. In particular, EPGs can use a grouping ofapplication endpoints in a network to apply connectivity and policy tothe group of applications. EPGs can act as a container for buckets orcollections of applications, or application components, and tiers forimplementing forwarding and policy logic. EPGs also allow separation ofnetwork policy, security, and forwarding from addressing by insteadusing logical application boundaries.

Cloud computing can also be provided in one or more networks to providecomputing services using shared resources. Cloud computing can generallyinclude Internet-based computing in which computing resources aredynamically provisioned and allocated to client or user computers orother devices on-demand, from a collection of resources available viathe network (e.g., “the cloud”). Cloud computing resources, for example,can include any type of resource, such as computing, storage, andnetwork devices, virtual machines (VMs), etc. For instance, resourcesmay include service devices (firewalls, deep packet inspectors, trafficmonitors, load balancers, etc.), compute/processing devices (servers,CPU's, memory, brute force processing capability), storage devices(e.g., network attached storages, storage area network devices), etc. Inaddition, such resources may be used to support virtual networks,virtual machines (VM), databases, applications (Apps), etc.

Cloud computing resources may include a “private cloud,” a “publiccloud,” and/or a “hybrid cloud.” A “hybrid cloud” can be a cloudinfrastructure composed of two or more clouds that inter-operate orfederate through technology. In essence, a hybrid cloud is aninteraction between private and public clouds where a private cloudjoins a public cloud and utilizes public cloud resources in a secure andscalable manner. Cloud computing resources can also be provisioned viavirtual networks in an overlay network, such as a VXLAN.

The disclosed technology addresses the need in the art for accurate andefficient routing schemes. Disclosed are systems, methods, andcomputer-readable storage media for forwarding tables for virtualnetworking devices. A brief introductory description of example systemsand networks, as illustrated in FIGS. 1 through 4, is disclosed herein.A detailed description of a forwarding scheme, default forwarding schemeor function, related concepts, and example variations, will then follow.These variations shall be described herein as the various embodimentsare set forth. The disclosure now turns to FIG. 1.

FIG. 1 illustrates an example network device 110 suitable forimplementing the present invention. Network device 110 includes a mastercentral processing unit (CPU) 162, interfaces 168, and a bus 115 (e.g.,a PCI bus). When acting under the control of appropriate software orfirmware, the CPU 162 is responsible for executing packet management,error detection, and/or routing functions, such as miscabling detectionfunctions, for example. The CPU 162 preferably accomplishes all thesefunctions under the control of software including an operating systemand any appropriate applications software. CPU 162 may include one ormore processors 163 such as a processor from the Motorola family ofmicroprocessors or the MIPS family of microprocessors. In an alternativeembodiment, processor 163 is specially designed hardware for controllingthe operations of router 110. In a specific embodiment, a memory 161(such as non-volatile RAM and/or ROM) also forms part of CPU 162.However, there are many different ways in which memory could be coupledto the system.

The interfaces 168 are typically provided as interface cards (sometimesreferred to as “line cards”). Generally, they control the sending andreceiving of data packets over the network and sometimes support otherperipherals used with the router 110. Among the interfaces that may beprovided are Ethernet interfaces, frame relay interfaces, cableinterfaces, DSL interfaces, token ring interfaces, and the like. Inaddition, various very high-speed interfaces may be provided such asfast token ring interfaces, wireless interfaces, Ethernet interfaces,Gigabit Ethernet interfaces, ATM interfaces, HSSI interfaces, POSinterfaces, FDDI interfaces and the like. Generally, these interfacesmay include ports appropriate for communication with the appropriatemedia. In some cases, they may also include an independent processorand, in some instances, volatile RAM. The independent processors maycontrol such communications intensive tasks as packet switching, mediacontrol and management. By providing separate processors for thecommunications intensive tasks, these interfaces allow the mastermicroprocessor 162 to efficiently perform routing computations, networkdiagnostics, security functions, etc.

Although the system shown in FIG. 1 is one specific network device ofthe present invention, it is by no means the only network devicearchitecture on which the present invention can be implemented. Forexample, an architecture having a single processor that handlescommunications as well as routing computations, etc. is often used.Further, other types of interfaces and media could also be used with therouter.

Regardless of the network device's configuration, it may employ one ormore memories or memory modules (including memory 161) configured tostore program instructions for the general-purpose network operationsand mechanisms for roaming, route optimization and routing functionsdescribed herein. The program instructions may control the operation ofan operating system and/or one or more applications, for example. Thememory or memories may also be configured to store tables such asmobility binding, registration, and association tables, etc.

FIG. 2A, and FIG. 2B illustrate example system embodiments. The moreappropriate embodiment will be apparent to those of ordinary skill inthe art when practicing the present technology. Persons of ordinaryskill in the art will also readily appreciate that other systemembodiments are possible.

FIG. 2A illustrates a conventional system bus computing systemarchitecture 200 wherein the components of the system are in electricalcommunication with each other using a bus 205. Exemplary system 200includes a processing unit (CPU or processor) 210 and a system bus 205that couples various system components including the system memory 215,such as read only memory (ROM) 220 and random access memory (RAM) 225,to the processor 210. The system 200 can include a cache of high-speedmemory connected directly with, in close proximity to, or integrated aspart of the processor 210. The system 200 can copy data from the memory215 and/or the storage device 230 to the cache 212 for quick access bythe processor 210. In this way, the cache can provide a performanceboost that avoids processor 210 delays while waiting for data. These andother modules can control or be configured to control the processor 210to perform various actions. Other system memory 215 may be available foruse as well. The memory 215 can include multiple different types ofmemory with different performance characteristics. The processor 210 caninclude any general purpose processor and a hardware module or softwaremodule, such as module 1 232, module 2 234, and module 3 236 stored instorage device 230, configured to control the processor 210 as well as aspecial-purpose processor where software instructions are incorporatedinto the actual processor design. The processor 210 may essentially be acompletely self-contained computing system, containing multiple cores orprocessors, a bus, memory controller, cache, etc. A multi-core processormay be symmetric or asymmetric.

To enable user interaction with the computing device 200, an inputdevice 245 can represent any number of input mechanisms, such as amicrophone for speech, a touch-sensitive screen for gesture or graphicalinput, keyboard, mouse, motion input, speech and so forth. An outputdevice 235 can also be one or more of a number of output mechanismsknown to those of skill in the art. In some instances, multimodalsystems can enable a user to provide multiple types of input tocommunicate with the computing device 200. The communications interface240 can generally govern and manage the user input and system output.There is no restriction on operating on any particular hardwarearrangement and therefore the basic features here may easily besubstituted for improved hardware or firmware arrangements as they aredeveloped.

Storage device 230 is a non-volatile memory and can be a hard disk orother types of computer readable media which can store data that areaccessible by a computer, such as magnetic cassettes, flash memorycards, solid state memory devices, digital versatile disks, cartridges,random access memories (RAMs) 225, read only memory (ROM) 220, andhybrids thereof.

The storage device 230 can include software modules 232, 234, 236 forcontrolling the processor 210. Other hardware or software modules arecontemplated. The storage device 230 can be connected to the system bus205. In one aspect, a hardware module that performs a particularfunction can include the software component stored in acomputer-readable medium in connection with the necessary hardwarecomponents, such as the processor 210, bus 205, display 235, and soforth, to carry out the function.

FIG. 2B illustrates an example computer system 250 having a chipsetarchitecture that can be used in executing the described method andgenerating and displaying a graphical user interface (GUI). Computersystem 250 is an example of computer hardware, software, and firmwarethat can be used to implement the disclosed technology. System 250 caninclude a processor 255, representative of any number of physicallyand/or logically distinct resources capable of executing software,firmware, and hardware configured to perform identified computations.Processor 255 can communicate with a chipset 260 that can control inputto and output from processor 255. In this example, chipset 260 outputsinformation to output 265, such as a display, and can read and writeinformation to storage device 270, which can include magnetic media, andsolid state media, for example. Chipset 260 can also read data from andwrite data to RAM 275. A bridge 280 for interfacing with a variety ofuser interface components 285 can be provided for interfacing withchipset 260. Such user interface components 285 can include a keyboard,a microphone, touch detection and processing circuitry, a pointingdevice, such as a mouse, and so on. In general, inputs to system 250 cancome from any of a variety of sources, machine generated and/or humangenerated.

Chipset 260 can also interface with one or more communication interfaces290 that can have different physical interfaces. Such communicationinterfaces can include interfaces for wired and wireless local areanetworks, for broadband wireless networks, as well as personal areanetworks. Some applications of the methods for generating, displaying,and using the GUI disclosed herein can include receiving ordereddatasets over the physical interface or be generated by the machineitself by processor 255 analyzing data stored in storage 270 or 275.Further, the machine can receive inputs from a user via user interfacecomponents 285 and execute appropriate functions, such as browsingfunctions by interpreting these inputs using processor 255.

It can be appreciated that example systems 200 and 250 can have morethan one processor 210 or be part of a group or cluster of computingdevices networked together to provide greater processing capability.

FIG. 3 illustrates a schematic block diagram of an example architecture300 for a network fabric 312. The network fabric 312 can include spineswitches 302 _(A), 302 _(B), . . . , 302 _(N) (collectively “302”)connected to leaf switches 304 _(A), 304 _(B), 304 _(c), . . . , 304_(N) (collectively “304”) in the network fabric 312.

Spine switches 302 can be L3 switches in the fabric 312. However, insome cases, the spine switches 302 can also, or otherwise, perform L2functionalities. Further, the spine switches 302 can support variouscapabilities, such as 40 or 10 Gbps Ethernet speeds. To this end, thespine switches 302 can include one or more 40 Gigabit Ethernet ports.Each port can also be split to support other speeds. For example, a 40Gigabit Ethernet port can be split into four 10 Gigabit Ethernet ports.

In some embodiments, one or more of the spine switches 302 can beconfigured to host a proxy function that performs a lookup of theendpoint address identifier to locator mapping in a mapping database onbehalf of leaf switches 304 that do not have such mapping. The proxyfunction can do this by parsing through the packet to the encapsulated,tenant packet to get to the destination locator address of the tenant.The spine switches 302 can then perform a lookup of their local mappingdatabase to determine the correct locator address of the packet andforward the packet to the locator address without changing certainfields in the header of the packet.

When a packet is received at a spine switch 302 _(i), the spine switch302 _(i) can first check if the destination locator address is a proxyaddress. If so, the spine switch 302 _(i) can perform the proxy functionas previously mentioned. If not, the spine switch 302 _(i) can lookupthe locator in its forwarding table and forward the packet accordingly.

Spine switches 302 connect to leaf switches 304 in the fabric 312. Leafswitches 304 can include access ports (or non-fabric ports) and fabricports. Fabric ports can provide uplinks to the spine switches 302, whileaccess ports can provide connectivity for devices, hosts, endpoints,VMs, or external networks to the fabric 312.

Leaf switches 304 can reside at the edge of the fabric 312, and can thusrepresent the physical network edge. In some cases, the leaf switches304 can be top-of-rack (“ToR”) switches configured according to a ToRarchitecture. In other cases, the leaf switches 304 can be aggregationswitches in any particular topology, such as end-of-row (EoR) ormiddle-of-row (MoR) topologies. The leaf switches 304 can also representaggregation switches, for example.

The leaf switches 304 can be responsible for routing and/or bridging thetenant packets and applying network policies. In some cases, a leafswitch can perform one or more additional functions, such asimplementing a mapping cache, sending packets to the proxy function whenthere is a miss in the cache, encapsulate packets, enforce ingress oregress policies, etc.

Moreover, the leaf switches 304 can contain virtual switchingfunctionalities, such as a virtual tunnel endpoint (VTEP) function asexplained below in the discussion of VTEP 408 in FIG. 4. To this end,leaf switches 304 can connect the fabric 312 to an overlay network, suchas overlay network 400 illustrated in FIG. 4.

Network connectivity in the fabric 312 can flow through the leafswitches 304. Here, the leaf switches 304 can provide servers,resources, endpoints, external networks, or VMs access to the fabric312, and can connect the leaf switches 304 to each other. In some cases,the leaf switches 304 can connect EPGs to the fabric 312 and/or anyexternal networks. Each EPG can connect to the fabric 312 via one of theleaf switches 304, for example.

Endpoints 310A-E (collectively “310”) can connect to the fabric 312 vialeaf switches 304. For example, endpoints 310A and 310B can connectdirectly to leaf switch 304A, which can connect endpoints 310A and 310Bto the fabric 312 and/or any other one of the leaf switches 304.Similarly, endpoint 310E can connect directly to leaf switch 304C, whichcan connect endpoint 310E to the fabric 312 and/or any other of the leafswitches 304. On the other hand, endpoints 310C and 310D can connect toleaf switch 304B via L2 network 306. Similarly, the wide area network(WAN) can connect to the leaf switches 304C or 304D via L3 network 308.

Endpoints 310 can include any communication device, such as a computer,a server, a switch, a router, etc. In some cases, the endpoints 310 caninclude a server, hypervisor, or switch configured with a VTEPfunctionality which connects an overlay network, such as overlay network400 below, with the fabric 312. For example, in some cases, theendpoints 310 can represent one or more of the VTEPs 408A-D illustratedin FIG. 4. Here, the VTEPs 408A-D can connect to the fabric 312 via theleaf switches 304. The overlay network can host physical devices, suchas servers, applications, EPGs, virtual segments, virtual workloads,etc. In addition, the endpoints 310 can host virtual workload(s),clusters, and applications or services, which can connect with thefabric 312 or any other device or network, including an externalnetwork. For example, one or more endpoints 310 can host, or connect to,a cluster of load balancers or an EPG of various applications.

Although the fabric 312 is illustrated and described herein as anexample leaf-spine architecture, one of ordinary skill in the art willreadily recognize that the subject technology can be implemented basedon any network fabric, including any data center or cloud networkfabric. Indeed, other architectures, designs, infrastructures, andvariations are contemplated herein.

FIG. 4 illustrates an exemplary overlay network 400. Overlay network 400uses an overlay protocol, such as VXLAN, VGRE, VO3, or STT, toencapsulate traffic in L2 and/or L3 packets which can cross overlay L3boundaries in the network. As illustrated in FIG. 4, overlay network 400can include hosts 406A-D interconnected via network 402.

Network 402 can include a packet network, such as an IP network, forexample. Moreover, network 402 can connect the overlay network 400 withthe fabric 312 in FIG. 3. For example, VTEPs 408A-D can connect with theleaf switches 304 in the fabric 312 via network 402.

Hosts 406A-D include virtual tunnel end points (VTEP) 408A-D, which canbe virtual nodes or switches configured to encapsulate andde-encapsulate data traffic according to a specific overlay protocol ofthe network 400, for the various virtual network identifiers (VNIDs)410A-D. Moreover, hosts 406A-D can include servers containing a VTEPfunctionality, hypervisors, and physical switches, such as L3 switches,configured with a VTEP functionality. For example, hosts 406A and 406Bcan be physical switches configured to run VTEPs 408A-B. Here, hosts406A and 406B can be connected to servers 404A-D, which, in some cases,can include virtual workloads through VMs loaded on the servers, forexample.

In some embodiments, network 400 can be a VXLAN network, and VTEPs408A-D can be VXLAN tunnel end points. However, as one of ordinary skillin the art will readily recognize, network 400 can represent any type ofoverlay or software-defined network, such as NVGRE, STT, or even overlaytechnologies yet to be invented.

The VNIDs can represent the segregated virtual networks in overlaynetwork 400. Each of the overlay tunnels (VTEPs 408A-D) can include oneor more VNIDs. For example, VTEP 408A can connect to virtual or physicaldevices or workloads residing in VNIDs 1 and 2; VTEP 408B can connect tovirtual or physical devices or workloads residing in VNIDs 1 and 3, VTEP408C can connect to virtual or physical devices or workloads residing inVNIDs 1, 2, 3, and another instance of VNID 2; and VTEP 408D can connectto virtual or physical devices or workloads residing in VNIDs 3 and 4,as well as separate instances of VNIDs 2 and 3. As one of ordinary skillin the art will readily recognize, any particular VTEP can, in otherembodiments, have numerous VNIDs, including more than the 4 VNIDsillustrated in FIG. 4. Moreover, any particular VTEP can connect tophysical or virtual devices or workloads residing in one or more VNIDs.

The traffic in overlay network 400 can be segregated logically accordingto specific VNIDs. This way, traffic intended for VNID 1 can be accessedby devices residing in VNID 1, while other devices residing in otherVNIDs (e.g., VNIDs 2, 3, and 4) can be prevented from accessing suchtraffic. In other words, devices or endpoints in specific VNIDs cancommunicate with other devices or endpoints in the same specific VNIDs,while traffic from separate VNIDs can be isolated to prevent devices orendpoints in other specific VNIDs from accessing traffic in differentVNIDs.

Each of the servers 404A-D and VMs 404E-L can be associated with arespective VNID or virtual segment, and communicate with other serversor VMs residing in the same VNID or virtual segment. For example, server404A can communicate with server 404C and VM 404E because they allreside in the same VNID, viz., VNID 1. Similarly, server 404B cancommunicate with VMs 404F, 404H, and 404L because they all reside inVNID 2.

Each of the servers 404A-D and VMs 404E-L can represent a single serveror VM, but can also represent multiple servers or VMs, such as a clusterof servers or VMs. Moreover, VMs 404E-L can host virtual workloads,which can include application workloads, resources, and services, forexample. On the other hand, servers 404A-D can host local workloads on alocal storage and/or a remote storage, such as a remote database.However, in some cases, servers 404A-D can similarly host virtualworkloads through VMs residing on the servers 404A-D.

VTEPs 408A-D can encapsulate packets directed at the various VNIDs 1-4in the overlay network 400 according to the specific overlay protocolimplemented, such as VXLAN, so traffic can be properly transmitted tothe correct VNID and recipient(s) (i.e., server or VM). Moreover, when aswitch, router, or other network device receives a packet to betransmitted to a recipient in the overlay network 400, it can analyze arouting table, such as a lookup table, to determine where such packetneeds to be transmitted so the traffic reaches the appropriaterecipient. For example, if VTEP 408A receives a packet from endpoint404B that is intended for endpoint 404H, VTEP 408A can analyze a routingtable that maps the intended endpoint, endpoint 404H, to a specificswitch that is configured to handle communications intended for endpoint404H. VTEP 408A might not initially know, when it receives the packetfrom endpoint 404B, that such packet should be transmitted to VTEP 408Cin order to reach endpoint 404H. Accordingly, by analyzing the routingtable, VTEP 408A can lookup endpoint 404H, which is the intendedrecipient, and determine that the packet should be transmitted to VTEP408C, as specified in the routing table based on endpoint-to-switchmappings or bindings, so the packet can be transmitted to, and receivedby, endpoint 404H as expected.

Each VTEP 408A-D typically maintains a forwarding table containing anentry for all the endpoints (i.e., servers and VMs) in the network 400,or at least those entries the VTEP knows about. However, as the networkgrows and becomes more complicated, so too does the forwarding table.Indeed, the forwarding table can become extremely large and complicatedin larger and more complex environments. This can be computationallyexpensive for the various switches and routers, and may require largeamounts of memory and storage to hold and process such forwardingtables.

As new devices are added to the network 400, the VTEPs attached to thedevices or residing in the network of the devices learn of the newdevices and update the forwarding table. The updated forwarding tablethen is converged so all the VTEPs 408A-D can update their forwardingtables and maintain an accurate account of the network.

To avoid large and complex routing tables, each of the VTEPs 408A-D canmaintain a simplified forwarding table which includes every local entry,including an entry for every VM and/or server connected to the VTEP.Here, each entry can include a respective address associated with theentry, as well as a scope ID, such as a VLAN ID, a VNID, a VRF ID, asubnet, a VPN ID, etc. The next hop forwarding information along with anentry can be set to point to the local host.

A “catch all” entry or default route can then be added to the forwardingtable to handle any other traffic, including any miss in the forwardingtable. The “catch all” entry or default route can point to a defaultforwarder function, such that any traffic addressed to a destinationaddress that is not a local address and is therefore not included in theforwarding table of the relevant VTEP, can be forwarded to the addressof the default forwarder function represented by the default route(i.e., the “catch all” entry). The default forwarder function can thenreceive the miss traffic, which would be forwarded from the local,specific VTEP to the default forwarder function, and forward or routethe traffic towards its appropriate destination. This way, theforwarding table at each VTEP can be kept smaller and much simpler,without any negative performance consequences.

The default forwarder function can be implemented in a standalone ordistributed fashion. In some embodiments, the default forwarder functioncan be implemented on leaf and spine switches in the network fabric,such as leaf and spine switches 304 and 302, respectively, on thenetwork fabric 312. In some cases, the leaf and spine switches 304 and302 can glean the reachability information, such as VM-to-hostreachability information, by learning this information from the dataplane of the fabric 312, or using a scalable control plane, for example.

This forwarding solution can be implemented as a scalable router andswitch solution on top of a overlay-aware fabric, such as fabric 312.Unlike conventional solutions, where every binding update is pushed toevery host or hypervisor, the scheme herein can work by limiting bindingupdates to only those impacted hosts or hypervisors. These can mean thata binding update is only needed to be pushed to a single hypervisor,except during a VM migration which may require up to two hypervisors. Insome embodiments, the binding update does not need to be explicitlypushed to the impacted hypervisor. Rather, when the VM is created or‘unstunned’, the hypervisor can automatically install the forwardingpolicy or scheme.

As one of ordinary skill in the art will readily recognize, the examplesand technologies provided above are simply for clarity and explanationpurposes, and can include many additional concepts and variations.

FIG. 5 illustrates a schematic block diagram of an exampleimplementation 500 of a forwarding policy according to one embodiment.Host 1 (406C) and host 2 (406D) connect to the fabric 312 via respectiveVTEPs 408C and 408D. Hosts 1 and 2 can be servers hosting virtualworkloads, VMs 404E-404L, residing in an overlay network, such asoverlay network 400, which connects to the fabric 312 via a virtualtunnel through the VTEPs 408C and 408D. In some cases, however, hosts 1and 2 can also connect to other servers on the overlay network, whichcan host one or more virtual or local workloads.

VTEPs 408C and 408D can be virtual switch or virtual routers configuredto connect the fabric 312 to an overlay network, such as overlay 400,through a virtual tunnel, using VTEP functionality. However, in somecases, VTEPs 408C and/or 408D can be physical switches or routersconfigured to implement VTEP functionality to connect the fabric 312 toan overlay network. For example, VTEPs 408C and/or 408D can be ToR orleaf switches, such as leaf switches 304 in FIG. 3.

As previously mentioned, VTEPs 408C and 408D connect VMs A-H (404E-L),hosted on hosts 1 and 2 (406A and 406B), to the fabric 312. Morespecifically, VTEP 408C can connect VMs A-D (404E-404H) to the fabric312, and VTEP 408D can connect VMs E-H (404I-L) to the fabric 312. Host1 (406C) can host VMs A-D (404E-H) and host 2 (406D) can host VMs E-H(404I-L).

The VMs A-H can have a configured IP address, as well as a scope ID,such as a VNID, a VLAN ID, a VRF, a VSID, etc. In order to route trafficbetween the fabric 312 and the VMs A-H (404E-L), each host can maintaina respective forwarding table 502 and 504, which maps the VMs A-H(404E-L) to an IP address of the fabric 312, an IP address of the host,a subnet, and/or a network segment, such as a VNID or VLAN for example.Moreover, the entries in each of the forwarding tables 502 and 504 canbe limited to the local entries for each of the hosts 406C-D and VTEPs408C-D. For example, the forwarding table 502 of host 1 (106C) caninclude the entries of VMs A-D (404E-H), without including entries forthe VMs in host 2, or any other host or external network. Similarly, theforwarding table 504 of host 2 (406D) can include the entries of VMs E-H(404I-L), without including entries for the VMs in host 1. This canensure that VTEPs 408C-D can forward traffic to their local VMs, withouthaving to include unnecessary entries that may potentially grow the sizeand complexity of the forwarding tables 502-504.

In addition, to allow VTEPs 408C-D to properly forward all other traffic(i.e., traffic intended for targets that are not local with respect tothe host and VTEP), the forwarding tables 502 and 504 can also include adefault route or “catch all” route in the table that points to a defaultforwarder function which can receive all non-local traffic and forwardit appropriately towards the intended target or destination. The defaultforwarder function can be a forwarder function running on a device inthe fabric 312. Thus, one or more switches or routers in the fabric 312can implement the default forwarder function to receive traffic from theVTEPs 408C-D that is not intended for hosts 1 and 2, respectively, andhandle the traffic by forwarding it as necessary. Accordingly, VTEPs408C-D can use their respective forwarding tables 502 and 504 to forwardlocal traffic intended to the local VMs, and send all other traffic backto the fabric 312 to the address in the forwarding tables 502 and 504associated with the device in the fabric 312 running the defaultforwarding function.

As more VMs are removed or added to host 1, for example, the forwardingtable 502 associated with host 1 can be updated to reflect such change.This way, the forwarding tables 502 and 504 can be maintained updatedwith respect to their local entries. However, any entry external totheir respective hosts 1 and 2 can be ignored to prevent the forwardingtables 502 and 504 from growing in size and complexity. This way, theforwarding tables 502 and 504 can remain effective yet efficient andsmall.

FIG. 6 illustrates an example forwarding table 502 implementing adefault forwarding function scheme. The forwarding table 502 can beimplemented by host 1 (406C) and VTEP 408C, as illustrated in FIG. 5. Asillustrated, the forwarding table 502 includes local entries 600, whichcorrespond to the local VMs E-H.

Each of the local entries 600 can map the client address (CA), referringto the address of the VM, to the reachability information for that VM.The reachability information can include the physical address of thehost or provider, the host ID, the network segment (e.g., VNID), and/orthe routing domain ID. The reachability information in the local entries600 can also specify whether the packet, when forwarded to the mappedaddress, needs to be encapsulated or decapsulated, and whatencapsulation/decapsulation protocol should be implemented, such asVXLAN or NVGRE protocol, for example. This reachability informationallows the VTEP 408C to receive a packet destined to any of the localVMs on host 1, and forward the packet as necessary to the appropriatephysical address, host, network, domain, and so forth.

The forwarding table 502 can also include a default route 602 for allother traffic. The default route 602 creates an entry that maps allother traffic, which is defined by the asterisks to denote trafficaddressed to any other destination, to a forwarder function. Theforwarder function can be used to properly handle all other traffic,including traffic intended to any other hosts, VMs, or servers in theoverlay network 400. For example, an incoming packet destined to VM E(404I) on host 2 and VNID 3, would fall within the scope of the defaultroute 602 and thus would be directed to the device running the defaultforwarder function. Thus, the incoming packet would be forwarded to thedevice running the default forwarder function, which would forward theincoming packet on to VM E (404I) at host 2 and VNID 3.

In some cases, the default forwarding function is implemented by theswitches 302 and/or 304 in the fabric 312. Accordingly, the defaultroute 602 can map all other traffic to the switches 302 and/or 304 inthe fabric 312, for handling by those switches using the defaultforwarder function as previously mentioned.

The default route 602 can also include any necessaryencapsulation/decapsulation information. For example, if the defaultroute 602 maps to a location which requires the incoming packets totraverse a virtual tunnel, then it can include the necessaryencapsulation information to allow the incoming packets to beencapsulated to traverse the virtual tunnel. Theencapsulation/decapsulation information can include the specificprotocol implemented for encapsulation/decapsulation, such as VXLAN orNVGRE, for example.

In some embodiments, the forwarding table 502 can include more than onedefault route for redundancy. Moreover, the default route 602 can alsobe split into multiple default routes. For example, if the defaultforwarder function is implemented in various devices, multiple defaultroutes can be created in the forwarding table 502 where specific rangesor types of traffic are designated to a default forwarder functiondevice, and other ranges or types of traffic are designated to anotherdefault forwarder function device.

Furthermore, while forwarding table 502 is shown as including localentries for local traffic and a default route for any other traffic,some embodiments of the forwarding table 502 can include non-localentries for specific destinations and/or types of traffic. For example,the forwarding table 502 can include non-local entries for a specifictenant, service, VNID, VLAN, device, and so forth. Moreover, theforwarding table 502 can also include other information, such astopology information, metrics, routing protocols, other static routes,priorities, gateways, hop information, paths and associated hops,subnets, rules, etc.

Having disclosed some basic system components and concepts, thedisclosure now turns to the exemplary method embodiment shown in FIG. 7.For the sake of clarity, the method is described in terms of a system110, as shown in FIG. 1, configured to practice the method. The stepsoutlined herein are exemplary and can be implemented in any combinationthereof, including combinations that exclude, add, or modify certainsteps.

The system 110 first identifies virtual machines hosted on a local hostconnected to the system 110, wherein the system 110 is a virtual tunnelendpoint associated with an overlay network (700). The virtual machinescan reside on one or more segments of the overlay network, such as VNIDsor VLANs. In some cases, the overlay network can be a VXLAN network.However, as one of ordinary skill in the art will readily recognize, theoverlay network can be based on any overlay protocol. The local host canbe a server connected to the system 110 and running the virtualmachines. For example, the local host can be a server running ahypervisor with one or more virtual machines. Here, the virtual machinescan reside on the overlay network.

In identifying the virtual machines, the system 110 can obtain any ofthe routing information of the virtual machines, which can include, forexample, the IP address of the virtual machines, the IP address of thelocal host, the MAC address of the local host, the network and/ornetwork segment identifier (ID), a routing domain ID, etc. The systemcan also compare routing information collected with its own configurednetworking information, such as subnet, IP address, network segment,routing domain, etc., to determine if the routing information should betreated as local for purposes of the forwarding policy, as describedbelow.

Next, the system 110 generates a forwarding table (702). The forwardingtable can be a lookup table used by the system 110 to route or forwardpackets it receives. To this end, the system 110 can use the forwardingtable to determine where to send an incoming packet it receives. Inother words, the forwarding table can help the system 110 identify thenext hop for the packet. Accordingly, the forwarding table can have hopinformation and mappings or bindings.

The system 110 then populates the forwarding table with local entriesincluding bindings for the virtual machines hosted on the local host(704) and adds a default route in the forwarding table pointing to adefault forwarder function configured to handle all non-local trafficrelative to the system 110 and the local host, wherein the defaultforwarder function is implemented on a network separate from the overlaynetwork (706). Thus, the system 110 can include all of the local entriesin the forwarding table and a default route for all other traffic. Thisway the system 110 can maintain a smaller and less complex forwardingtable, by limiting the table to local entries and a “catch all” ordefault route for all other addresses and devices.

As the network, the fabric, and the overlay network grows, the system110 can maintain forwarding tables as described above, without adding agreat deal of unnecessary entries and complexity. Moreover, system 110does not need to maintain entries for other hosts or remote virtualmachines, and the network and networking devices do not need to convergerouting information, which could further add to the burden on thenetwork and complexity of the routing or forwarding tables.

The system 110 can add and delete local entries as local virtualmachines are added or removed from the local host. For example, if alocal virtual machine is migrated to another host and/or networksegment, the local entry of that virtual machine can be removed from theforwarding table. On the other hand, the update can also be pushed tothe hosts or hypervisors affected by the changes, which would allowthose hosts or hypervisors to update their forwarding table accordingly.The other hosts or hypervisors can similarly implement the forwardingpolicy described above.

The network fabric can include spine and leaf switches, such as fabric312 illustrated in FIG. 3. One or more of the spine and leaf switchescan implement the default forwarder function, to allow non-local trafficforwarded from the system 110 (or any other VTEP or switch implementingthe forwarding policy) to be routed to the next hop. In some cases, thedefault forwarder function can be implemented in a distributed fashion,such that multiple switches in the fabric 312 can implement thefunctionalities. The leaf and spine switches can obtain the VM-to-hostreachability information by learning such information from the dataplane or using a scalable control plane, for example.

For clarity of explanation, in some instances the present technology maybe presented as including individual functional blocks includingfunctional blocks comprising devices, device components, steps orroutines in a method embodied in software, or combinations of hardwareand software.

In some embodiments the computer-readable storage devices, mediums, andmemories can include a cable or wireless signal containing a bit streamand the like. However, when mentioned, non-transitory computer-readablestorage media expressly exclude media such as energy, carrier signals,electromagnetic waves, and signals per se.

Methods according to the above-described examples can be implementedusing computer-executable instructions that are stored or otherwiseavailable from computer readable media. Such instructions can comprise,for example, instructions and data which cause or otherwise configure ageneral purpose computer, special purpose computer, or special purposeprocessing device to perform a certain function or group of functions.Portions of computer resources used can be accessible over a network.The computer executable instructions may be, for example, binaries,intermediate format instructions such as assembly language, firmware, orsource code. Examples of computer-readable media that may be used tostore instructions, information used, and/or information created duringmethods according to described examples include magnetic or opticaldisks, flash memory, USB devices provided with non-volatile memory,networked storage devices, and so on.

Devices implementing methods according to these disclosures can comprisehardware, firmware and/or software, and can take any of a variety ofform factors. Typical examples of such form factors include laptops,smart phones, small form factor personal computers, personal digitalassistants, rackmount devices, standalone devices, and so on.Functionality described herein also can be embodied in peripherals oradd-in cards. Such functionality can also be implemented on a circuitboard among different chips or different processes executing in a singledevice, by way of further example.

The instructions, media for conveying such instructions, computingresources for executing them, and other structures for supporting suchcomputing resources are means for providing the functions described inthese disclosures.

Although a variety of examples and other information was used to explainaspects within the scope of the appended claims, no limitation of theclaims should be implied based on particular features or arrangements insuch examples, as one of ordinary skill would be able to use theseexamples to derive a wide variety of implementations. Further andalthough some subject matter may have been described in languagespecific to examples of structural features and/or method steps, it isto be understood that the subject matter defined in the appended claimsis not necessarily limited to these described features or acts. Forexample, such functionality can be distributed differently or performedin components other than those identified herein. Rather, the describedfeatures and steps are disclosed as examples of components of systemsand methods within the scope of the appended claims. Moreover, claimlanguage reciting “at least one of” a set indicates that one member ofthe set or multiple members of the set satisfy the claim.

We claim:
 1. A method comprising: identifying virtual machines hosted ona local host associated with a switch component comprising a virtualtunnel endpoint associated with an overlay network; generating, via aprocessor, a forwarding table for the switch component and populatingthe forwarding table only with local entries comprising bindings orentries for the virtual machines hosted on the local host; adding adefault route in the forwarding table pointing to a forwarder functionconfigured to handle all non-local traffic relative to the switchcomponent, wherein the forwarder function associated with the defaultroute is implemented on a network separate from the overlay network; andupdating the forwarding table only based on updates to the virtualmachines hosted on the local host or addition of new virtual machineshosted on the local host.
 2. The method of claim 1, wherein the switchcomponent is hosted by the local host, and wherein the switch componentcomprises one of a virtual switch or a virtual router.
 3. The method ofclaim 1, wherein each of the local entries comprises a respectivevirtual machine address and a respective network scope identifier. 4.The method of claim 1, wherein the non-local traffic comprises traffichaving a destination that is not hosted by the local host.
 5. The methodof claim 1, wherein the local entries comprise respective networksegment identifiers, wherein the respective network segment identifierscomprise at least one of overlay segment identifiers, virtual local areanetwork identifiers, and virtual routing and forwarding identifiers. 6.The method of claim 1, wherein the network comprises a network fabricconnected to the overlay network, wherein the forwarder function resideson the network fabric, the switch component connecting the networkfabric to the overlay network.
 7. The method of claim 6, wherein thevirtual machines reside in the overlay network and communicate with thenetwork fabric via a tunnel provided by the switch component, whereinthe overlay network comprises a virtual extensible local area network(VXLAN).
 8. The method of claim 6, wherein the default route is used toroute traffic intended to other virtual machines in the overlay network,the other virtual machines being hosted by other hosts.
 9. The method ofclaim 6, wherein the network fabric comprises spine and leaf networkdevices in a spine and leaf topology, wherein the forwarder function ishosted or performed by a plurality of the spine and leaf networkdevices.
 10. The method of claim 1, further comprising removing a localentry from the forwarding table associated with a virtual machine on thelocal host when the virtual machine is at least one of migrated toanother host or removed from the local host.
 11. The method of claim 1,further comprising adding a local entry to the forwarding tableassociated with a virtual machine on the local host when the virtualmachine is at least one of added to the local host or migrated fromanother host to the local host.
 12. A system comprising: one or moreprocessors; and a computer-readable storage medium having stored thereininstructions which, when executed by the one or more processors, causethe one or more processors to perform operations comprising: identifyingvirtual machines hosted on a local host associated with a switch, theswitch comprising a virtual tunnel endpoint associated with an overlaynetwork; generating a forwarding table for the switch and populating theforwarding table only with local entries comprising bindings or entriesfor the virtual machines hosted on the local host; adding a defaultroute in the forwarding table pointing to one or more devices running aforwarder function, wherein the forwarder function is configured tohandle all non-local traffic relative to at least one of the switch andthe local host; and updating the forwarding table only based on updatesto the virtual machines hosted on the local host or addition of newvirtual machines hosted on the local host.
 13. The system of claim 12,wherein the execution of the instructions stored on thecomputer-readable storage medium further cause the one or moreprocessors to update the forwarding table by updating the local entriesin the forwarding table when a local virtual machine is migrated to thelocal host, added to the local host, or removed from the local host. 14.The system of claim 12, wherein the switch comprises a virtual switch,the non-local traffic comprising traffic having a destination that isnot hosted by the local host.
 15. The system of claim 12, wherein thelocal entries include at least one of respective addresses associatedwith local virtual machines, respective network segment identifiersassociated with the local virtual machines, and an address associatedwith the local host hosting the local virtual machines.
 16. The systemof claim 12, wherein the execution of the instructions stored on thecomputer-readable storage medium cause the one or more processors toupdate the forwarding table only when a virtual machine is added to thelocal host or removed from the local host, and wherein updates to otherforwarding tables associated with different hosts or switches are notpropagated to the forwarding table unless such updates are associatedwith the virtual machine being added to the local host or removed fromthe local host.
 17. A non-transitory computer-readable storage mediumhaving stored therein instructions which, when executed by a processor,cause the processor to perform operations comprising: receiving, via aswitch comprising a virtual tunnel endpoint connected to an overlaynetwork, an incoming packet intended for a destination address;analyzing a forwarding table to identify a next hop for the packet,wherein the forwarding table comprises only local entries for localdestinations relative to the switch and a default route entry for allnon-local traffic, the local destinations corresponding to virtual nodeshosted on a same host as the switch and wherein the forwarding table isupdated only based on updates to the virtual nodes hosted on the samehost or addition of new virtual nodes hosted on the same host; andforwarding the incoming packet to the next hop based on an entry in theforwarding table, the entry comprising: at least one of the localentries when the next hop is one of the virtual nodes hosted on the samehost as the switch; or the default route entry when the next hop is notone of the virtual nodes hosted on the same host as the switch.
 18. Thenon-transitory computer-readable storage medium of claim 17, wherein thevirtual tunnel endpoint connects the virtual nodes hosted on the samehost to a network fabric via a tunnel between the overlay network andthe network fabric, wherein the default route entry corresponds to oneor more nodes in the network fabric.
 19. The non-transitorycomputer-readable storage medium of claim 17, wherein the default routeentry maps to a forwarder function implemented by a plurality of networkdevices on the network fabric, and wherein the plurality of networkdevices comprises at least one of spine and leaf switches on the networkfabric.
 20. The non-transitory computer-readable storage medium of claim17, wherein the virtual nodes hosted on the same host as the switch areassociated with a plurality of virtual network domains comprisingdifferent overlay network segments.